// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-

//****************************************************************
// Function that will calculate the desired direction to fly and distance
//****************************************************************
void navigate()
{
	// do not navigate with corrupt data
	// ---------------------------------
	if (g_gps->fix == 0){
		g_gps->new_data = false;
		return;
	}

	if(next_WP.lat == 0){
		return;
	}

	// waypoint distance from plane
	// ----------------------------
	wp_distance = get_distance(&current_loc, &next_WP);

	if (wp_distance < 0){
		//gcs.send_text_P(SEVERITY_HIGH,PSTR("<navigate> WP error - distance < 0"));
		//Serial.println(wp_distance,DEC);
		//print_current_waypoints();
		return;
	}

	// target_bearing is where we should be heading
	// --------------------------------------------
	target_bearing 	= get_bearing(&current_loc, &next_WP);

	// nav_bearing will includes xtrac correction
	// ------------------------------------------
	nav_bearing = target_bearing;

	// Sum the # of times around the WP
	loiter_delta = (target_bearing - old_target_bearing)/100;

	// reset the old value
	old_target_bearing = target_bearing;

	// wrap values
	if (loiter_delta > 180) loiter_delta -= 360;
	if (loiter_delta < -180) loiter_delta += 360;
	loiter_sum += abs(loiter_delta);
}

bool check_missed_wp()
{
	long temp 	= target_bearing - saved_target_bearing;
	temp 		= wrap_180(temp);
	return (abs(temp) > 10000);	//we pased the waypoint by 10 °
}

#if 0
// Disabled for now
void calc_distance_error()
{
	distance_estimate 	+= (float)g_gps->ground_speed * .0002 * cos(radians(bearing_error * .01));
	distance_estimate 	-= DST_EST_GAIN * (float)(distance_estimate - GPS_wp_distance);
	wp_distance  		= max(distance_estimate,10);
}
#endif


void calc_bearing_error()
{
	bearing_error = nav_bearing - g_gps->ground_course;
	bearing_error 	= wrap_180(bearing_error);
}

void calc_altitude_error()
{
	// limit climb rates
	target_altitude = next_WP.alt - ((float)((wp_distance -20) * offset_altitude) / (float)(wp_totalDistance - 20));
	if(prev_WP.alt > next_WP.alt){
		target_altitude = constrain(target_altitude, next_WP.alt, prev_WP.alt);
	}else{
		target_altitude = constrain(target_altitude, prev_WP.alt, next_WP.alt);
	}
	/*
	#if AIRSPEED_SENSOR
		// special thanks to Ryan Beall for this one
		float pitch_angle 	= pitch_sensor - AOA; // pitch_angle = pitch sensor - angle of attack of your plane at level *100 (50 = .5°)
		pitch_angle			= constrain(pitch_angle, -2000, 2000);
		float scale			= sin(radians(pitch_angle * .01));
		altitude_estimate 	+= (float)airspeed * .0002 * scale;
		altitude_estimate 	-= ALT_EST_GAIN * (float)(altitude_estimate - current_loc.alt);

		// compute altitude error for throttle control
		altitude_error  = target_altitude - altitude_estimate;
	#else
		altitude_error 	= target_altitude - current_loc.alt;
	#endif
	*/
	altitude_error 	= target_altitude - current_loc.alt;
}

long wrap_360(long error)
{
	if (error > 36000)	error -= 36000;
	if (error < 0)		error += 36000;
	return error;
}

long wrap_180(long error)
{
	if (error > 18000)	error -= 36000;
	if (error < -18000)	error += 36000;
	return error;
}

void update_loiter()
{
	float power;

	if(wp_distance <= loiter_radius){
		power = float(wp_distance) / float(loiter_radius);
		nav_bearing += (int)(9000.0 * (2.0 + power));

	}else if(wp_distance < (loiter_radius + LOITER_RANGE)){
		power = -((float)(wp_distance - loiter_radius - LOITER_RANGE) / LOITER_RANGE);
		power = constrain(power, 0, 1);
		nav_bearing -= power * 9000;

	}else{
		update_crosstrack();
		loiter_time = millis();			// keep start time for loiter updating till we get within LOITER_RANGE of orbit
	}

	if (wp_distance < loiter_radius){
		nav_bearing += 9000;
	}else{
		nav_bearing -= 100 * M_PI / 180 * asin(loiter_radius / wp_distance);
	}

	update_crosstrack;
	nav_bearing = wrap_360(nav_bearing);
}

void update_crosstrack(void)
{
	// Crosstrack Error
	// ----------------
	if (cross_track_test() < 5000) {	 // If we are too far off or too close we don't do track following
		crosstrack_error = sin(radians((target_bearing - crosstrack_bearing) / 100)) * wp_distance;	 // Meters we are off track line
		nav_bearing += constrain(crosstrack_error * crosstrack_gain, -crosstrack_entry_angle, crosstrack_entry_angle);
		nav_bearing = wrap_360(nav_bearing);
	}
}

long cross_track_test()
{
	long temp 	= target_bearing - crosstrack_bearing;
	temp 		= wrap_180(temp);
	return abs(temp);
}

void reset_crosstrack()
{
	crosstrack_bearing 	= get_bearing(&current_loc, &next_WP);	// Used for track following
}

int get_altitude_above_home(void)
{
	// This is the altitude above the home location
	// The GPS gives us altitude at Sea Level
	// if you slope soar, you should see a negative number sometimes
	// -------------------------------------------------------------
	return current_loc.alt - home.alt;
}

long get_distance(struct Location *loc1, struct Location *loc2)
{
	//if(loc1->lat == 0 || loc1->lng == 0)
	//	return -1;
	//if(loc2->lat == 0 || loc2->lng == 0)
	//	return -1;
	float dlat 		= (float)(loc2->lat - loc1->lat);
	float dlong		= ((float)(loc2->lng - loc1->lng)) * scaleLongDown;
	return sqrt(sq(dlat) + sq(dlong)) * .01113195;
}

long get_alt_distance(struct Location *loc1, struct Location *loc2)
{
	return abs(loc1->alt - loc2->alt);
}

long get_bearing(struct Location *loc1, struct Location *loc2)
{
	long off_x = loc2->lng - loc1->lng;
	long off_y = (loc2->lat - loc1->lat) * scaleLongUp;
	long bearing =  9000 + atan2(-off_y, off_x) * 5729.57795;
	if (bearing < 0) bearing += 36000;
	return bearing;
}
